Many people underestimate the importance of leaving a sizable portion of your hard disk free. Imagine trying to cook a gourmet meal with 95% of your kitchen counters covered in supplies (even if those supplies are well-organized and tasty)! We expect our computers to perform a similar feat when we operate with hard drives stuffed to the brim (sound familiar, MacBook Air users?).
From what I’ve read, maintaining ~20% free is recommended. If you want to quickly check how much space you have available on your Mac, go Apple –> About this Mac –> Storage
Less than 20% free? You have two options: Increase the size of your hard disk, or make some space.
“Great! I just have to delete some stuff and make room!” So you start with the “easy-gets”: Downloads folder (wow–totally useless files from 3 years ago!), those Breaking Bad episodes you still have hanging around, maybe trashing a few crap photos. Quickly, you realize how time-consuming it is to free up space, and that many of the files you are deleting are actually quite small and insignificant. You may be wondering: What the #&$% is taking up so much space?!
This is where Disk Inventory X comes in. A free program that will give you a detailed, graphical report that very quickly lets you know who your GB-hogs are. It will automatically sort your folders based on size. You can expand each folder to show more detail, and the corresponding colored-box will be highlighted.
Immediately, you will realize you have some unpleasant work to do (nobody likes chugging through all those photos!). But, hopefully, you can find a few quickies that will give you some breathing room. Chances are high that your media files are going to taking up a huge amount of space. I recommend using flagging to pick the ‘keepers’, then trash the rest! Also worth checking: Downloads folder(s), Applications (do you really actually use all of them?), iTunes media (watch out for duplicates!), Movies (really–are you going to ever need a movie file after you’ve seen it once?).